Occupancy detection

ABSTRACT

A system for determining occupancy includes a first luminaire having a first camera to detect a first occupant and a second luminaire having a second camera to detect a second occupant. The system further includes a processor to determine whether the first camera and the second camera have a common visual field and to determine whether the first occupant and the second occupant are the same occupant in response to determining that the first camera and the second camera have a common visual field.

RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application No. 62/264,132, filed Dec. 7, 2015, andtitled “Occupancy Detection,” the entire content of which isincorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to occupancy detection, inparticular to improved accuracy of occupant count detection.

BACKGROUND

LED solid state luminaires provide a broad, uniform, powered, electricalplatform for the integration of sensing equipment such as image sensors(e.g., cameras). The sensors may not only be used to view and trackactivity, but also to establish occupancy. That is, the sensors may beused to establish whether one or more occupants are present in a spaceand the number of occupants in the space—both whetheroccupied/unoccupied and number of occupants. While some image sensorsmay recognize and count, for example, humans and/or objects, withintheir respective visual fields, such multiple image sensors that are inclose proximity of the same monitored area may all count the sameperson. For example, multiple camera sensors that have overlappingfields of vision may each count the same entity, which may lead to atotal tally of occupants that is more than the actual number ofoccupants. Because the sensors may not have fully overlapping fields ofvision, using the count from just one of the sensors may lead to a totaltally of occupants that is fewer than the actual number of occupants.Thus, while individual image sensors can count objects or humans intheir own visual field, multiple image sensors viewing the same area maylead to a miscount of objects and/or humans.

Thus, in some applications, systems and methods that improve occupancydetection by determining whether multiple image sensors have a commonvisual field are desirable.

SUMMARY

The present disclosure relates generally to occupancy detection, inparticular to improved accuracy of occupant count detection. In anexample embodiment, a system for determining occupancy includes a firstluminaire having a first camera to detect a first occupant and a secondluminaire having a second camera to detect a second occupant. The systemfurther includes a processor to determine whether the first camera andthe second camera have a common visual field and to determine whetherthe first occupant and the second occupant are the same occupant inresponse to determining that the first camera and the second camera havethe common visual field.

In another example embodiment, a method for determining occupancyincludes determining whether a first camera of a first luminaire and asecond camera of a second luminaire have a common visual field. Themethod further includes detecting, by the first camera of the firstluminaire, a first occupant in the common visual field, and detecting,by the second camera of the second luminaire, a second occupant in thecommon visual field. The method also includes determining, by aprocessor, whether the first occupant and the second occupant are thesame occupant in response to determining that the first camera and thesecond camera have the common visual field.

In another example embodiment, a system for determining occupancyincludes a first luminaire having a first camera to capture a firstimage, and a second luminaire having a second camera to capture a secondimage. The system further includes a processor to determine whether thefirst camera and the second camera have a common visual field and todetermine whether a first occupant in the first image and a secondoccupant in the second image are the same occupant in response todetermining that the first camera and the second camera have a commonvisual field.

These and other aspects, objects, features, and embodiments will beapparent from the following description and the appended claims.

BRIEF DESCRIPTION OF THE FIGURES

Reference will now be made to the accompanying drawings, which are notnecessarily drawn to scale, and wherein:

FIG. 1 illustrates an occupant detection system that uses luminaireintegrated cameras according to an example embodiment;

FIG. 2 illustrates an image captured with a camera of the system of FIG.1 in accordance with an example embodiment;

FIG. 3 illustrates a system of occupant detection according to anotherexample embodiment;

FIG. 4 illustrates a system of occupant detection according to anotherexample embodiment;

FIG. 5 illustrates a flowchart of a method of occupant detectionaccording to an example embodiment; and

FIG. 6 illustrates a flowchart of a method of occupant detectionaccording to another example embodiment.

The drawings illustrate only example embodiments of the disclosure andare therefore not to be considered limiting of its scope, as thedisclosure may admit to other equally effective embodiments. Theelements and features shown in the drawings are not necessarily toscale, emphasis instead being placed upon clearly illustrating theprinciples of the example embodiments. In the drawings, referencenumerals designate like or corresponding, but not necessarily identical,elements.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

In the following paragraphs, particular embodiments will be described infurther detail by way of example with reference to the figures. In thedescription, well known components, methods, and/or processingtechniques are omitted or briefly described. Furthermore, reference tovarious feature(s) of the embodiments is not to suggest that allembodiments must include the referenced feature(s).

Turning now to the drawings, FIG. 1 illustrates an occupant detectionsystem 100 that uses luminaire integrated cameras according to anexample embodiment. In some example embodiments, the system 100 includesa first luminaire 102 and a second luminaire 106. The first luminaire102 includes a camera 104. The second luminaire 106 includes a camera108. For example, the luminaries 102, 106 may be installed in aconference room, a hallway, an office, etc. In some example embodiments,the system 100 may include a third luminaire 114 that includes a camera116.

In some example embodiments, whether the camera 104 has a common visualfield with the camera 108 may be determined to establish whether imagescaptured by the cameras 104, 108 may be images of the same visual fieldor images of at least partially overlapping visual fields of the cameras104, 108. A determination may also be made whether the camera 116 hasthe same visual area as the cameras 104, 108. A visual field of thecamera 104 refers to an area of which the camera 104 can capture animage. A visual field of the camera 108 refers to an area of which thecamera 108 can capture an image. A visual field of the camera 116 refersto an area of which the camera 116 can capture an image. A visual fieldof each luminaire 102, 106, 114 with respect to illumination isconsidered to be the same as the visual field of the respective camera104, 108, 116 with respect to capturing an image. For example, thecameras 104, 108, 116 may be positioned such that the area illuminatedby each of the luminaires 102, 106, 114 may also be captured by therespective camera 104, 108, 116.

To illustrate, the camera 104 is considered to have the same visualfield as the luminaire 102, the camera 108 is considered to have thesame visual field as the luminaire 106, and the camera 116 is consideredto have the same visual field as the luminaire 114. Because the cameras104, 108, 106 are attached to or located at or within the luminaires,the proximity or spatial relationship between the cameras 104, 108, 106may be established by establishing the proximity or spatial relationshipbetween the luminaires 102, 106, 114. For example, the proximity orspatial relationship between the luminaires 102, 106, 114 that isestablished during a commissioning of the luminaires 102, 106, 114 maybe used to determine whether any of the cameras 104, 108, 106 have atleast partially overlapping visual fields. In some example embodiments,a common visual field refers to a combination of visual fields of twocameras (e.g., visual fields of the cameras 104 and 108) even when theoverlapping of the visual fields of the cameras is partial.Alternatively, a common visual field may refer to the overlapping areaof the visual fields of the cameras.

During or after commissioning, the system 100 may determine whether thecameras 104, 108, 116 have a common visual area in one of several ways.For example, each luminaire 102, 106, 114 may indicate its presence in aparticular area by emitting a light in a pattern that is unique to theparticular luminaire. To illustrate, each luminaire 102, 106, 114 mayemit a light that is modulated with identifier data that identifies theparticular luminaire. Any of the other luminaires that receive theemitted light can determine from the received light that the particularluminaire that emitted the light is in the same visual field as theluminaire that received the light. The emitted light may be a visiblelight or a non-visible light (e.g., infrared light).

In some example embodiments, a visual inspection may be done first todetermine that the cameras 104, 108 have the same or a common visualfield. Whether movements are detected by both cameras 104, 108 or byprocessors that receive image data from the cameras 104, 108 may also bedone prior to normal operation of the cameras is started.

To illustrate, the luminaire 102 may determine that it is in the samevisual field as the luminaire 104, and the luminaire 104 may determinethat it is in the same visual field as the luminaire 102. The luminaires102, 104 may determine that they are in a different visual field fromthe luminaire 114 because light emitted by the luminaire 114 does notreach the luminaires 102, 104. Similarly, the luminaire 114 maydetermine that luminaires 102, 104 are in a different visual field. Forexample, a visual field 112 and a visual field 120 may be separated by awall 122. Alternatively, the third luminaire 114 may be installed in thesame areas as the first and second luminaires 102, 106 but may belocated such that the luminaire 114 does not have a common visual fieldwith the luminaires 102, 106. Examples of determining visual fields ofluminaires are described in U.S. patent application Ser. No. 14/215,758,the entire content of which is incorporated herein by reference.

In some example embodiments, each luminaire 102, 106, 114 may determinewhether the other luminaries have the same or different visual field,for example, using a processor that can perform such function. Forexample, a processor in the luminaire 102 may determine that theluminaire 106 has a common visual field with the luminaire 102 byprocessing information extracted from a light received by luminaire 102.To illustrate, a light may be received, for example, by the camera 104and the processor may process (e.g., demodulate and/or decode, etc.) anelectrical signal generated from/based on the received light. Theprocessor in the luminaire 102 may determine that the luminaire 102 hasa common visual field with the luminaire 106, if the processordetermines that the information includes the identifier of the luminaire106. Each luminaire 106, 114 may perform a similar operation todetermine whether one or more other luminaires have a common visualfield with the particular luminaire 104, 106.

Alternatively or in addition, instead of each luminaire processing theinformation extracted from a respective received light, the luminaires102, 106, 114 may transmit the information extracted from a receivedlight to an external processor that identifies the luminaires that havea common visual field and the luminaires that have different visualfields. As indicated above some example embodiments, a determination ofthe visual fields of the luminaires 102, 106, 114 may be performed priorto a normal operation of the cameras to detect occupants (e.g., duringcommissioning of the luminaires).

In some example embodiments, the camera 104 and the camera 108 maydetect an occupant (e.g., a person) 110 in a visual field 112. Thecamera 104 and the camera 108 may detect the occupant 110 using methodsknown to those of ordinary skill in the art with the benefit of thisdisclosure. For example, the cameras 104, 108 may detect the occupant110 based on the pixel representation of the occupant 110. Toillustrate, the pixel representation of the occupant 100 may correspondto an expected pixel representation of a person. For example, number ofpixels, pixel intensity, etc. may be used to detect the occupant 110 inthe visual field 112. In some alternative embodiments, methods that donot use pixel mapping (i.e., pixel representation of an image) known tothose of ordinary skill in the art may be used to detect the occupant110.

In some example embodiments, the camera 116 of the third luminaire 114may detect an occupant 118 in a visual field 120. The camera 116 maydetect the occupant 118 using the same or similar methods used by thecameras 104, 108. For example, the camera 116 may detect the occupant118 based on the pixel representation of the occupant 118 with respectto an expected pixel representation of a person. The number of pixels,pixel intensity, etc. may be used to detect the occupant 118 in thevisual field 118. Alternatively, methods that do not use pixel mappingknown to those of ordinary skill in the art may be used to detect theoccupant 118.

In some example embodiments, a remote processor may receive image datafrom the camera 104 and detect the occupant 110 by processing the imagedata. The remote processor may also receive image data from the camera108 and detect the occupant 110 by processing the image data. The remoteprocessor may also receive image data from the camera 116 and detect theoccupant 118 by processing the image data.

In some alternative embodiments, a processor that is at one of theluminaires 102, 106, 114 may receive image data from the camera 104 anddetect the occupant 110 by processing the image data from the camera104. The processor that is at one of the luminaires 102, 106, 114 mayalso receive image data from the camera 108 and detect the occupant 110by processing the image data from the camera 108. The processor that isat one of the luminaires 102, 106, 114 may also receive image data fromthe camera 116 and detect the occupant 118 by processing the image datafrom the camera 116. For example, a processor that is integrated in theluminaire 102 may receive image data from the cameras 104, 108, 116 anddetect the occupant 110 and the occupant 118 by processing the receivedimage data.

After the detection of the occupant 110 and the occupant 118 by thecameras 104, 108, 116, the remote processor (e.g., the processor shownin FIG. 3), or the processor at one of the luminaires 102, 106, 114,(e.g., the processor shown in FIG. 4), a processor (e.g., the processorshown in FIG. 3 or 4) may determine whether one or two occupants aredetected by the cameras 104, 108. To illustrate, the processor may firstdetermine whether the cameras 104, 108 have a common visual field. Forexample, the processor may retrieve information that indicates whetherthe cameras 104, 108 have a common visual area. The information may beestablished during or after commissioning of the luminaires 102, 106,114. Alternatively, the processor may further process the information todetermine whether the cameras 104, 108 have a common visual area. Afterdetermining that the cameras 104, 108 have a common visual field, theprocessor may determine whether the occupant 110 in the image capturedby the camera 104 is the same occupant as the occupant in the imagecaptured by the camera 108.

After the detection of the occupant 110 and the occupant 118 by thecameras 104, 108, 116, the remote processor (e.g., the processor shownin FIG. 3), or the processor at one of the luminaires 102, 106, 114,(e.g., the processor shown in FIG. 4), the processor may also determinewhether the occupant 110 in the image captured by the camera 104 and theoccupant 110 in the image captured by the camera 108 is/are the same ordifferent from the occupant 118. To do so, the processor may firstdetermine, in the same manner as described above with respect to thecameras 104, 108, whether the cameras 104, 108 each have a common visualfield with the camera 116. After determining that the cameras 104, 108do not have a common visual field with the camera 116, the processor maydetermine that the occupant 118 is distinct from the occupant 110.

In some example embodiments, a direction of movement of the occupant 110captured by the camera 104 may be compared against the direction ofmovement of the occupant 110 captured by the camera 108 to determinewhether the same occupant or different occupants are captured by thecameras 104, 108.

In some example embodiments, the camera 104 may determine a direction ofmovement of the occupant 110 based on the images captured by the camera104. For example, the camera 104 may determine the direction of movementof the occupant 110 by comparing pixel mappings of two or more imagescaptured by the camera 104. To illustrate, the relative position of theoccupant 110 in multiple images captured by the camera 104 may indicatethe direction of movement of the occupant 110. The camera 104 mayprovide the direction information to a remote processor (e.g., theprocessor shown in FIG. 3) or to a processor that is in one of theluminaires 102, 106, 114, (e.g., the processor shown in FIG. 4).

In some example embodiments, the camera 108 may determine a direction ofmovement of the occupant 110 based on the images captured by the camera108, for example, by comparing pixel mappings of two or more imagescaptured by the camera 108. The camera 108 may provide the directioninformation to a remote processor (e.g., the processor shown in FIG. 3)or to a processor that is in one of the luminaires 102, 106, 114 (e.g.,the processor shown in FIG. 4).

In some example embodiments, the processor (e.g., the processor shown inFIG. 3 or 4) may receive the direction information from the cameras 104,108 and compare the direction of movement of the occupant 110 determinedby the camera 104 against the direction of movement of the occupant 110determined by the camera 108 to determine whether the same occupant ordifferent occupants are in the images captured by the cameras 104, 108.For example, if the comparison indicates the same direction of movement,the processor may conclude that the same occupant 110 was captured bythe cameras 104, 108. If the comparison indicates different directionsof movement, the processor may conclude that the occupant 110 capturedby the cameras 104, 108 are two different occupants.

In some example embodiments, the processor (e.g., the processor shown inFIG. 3 or 4), instead or in addition to the cameras 104, 108, maydetermine the directions of movements of the occupant 110 detected by orbased on images from the cameras 104, 108. To illustrate, a remoteprocessor (e.g., the processor shown in FIG. 3) may receive multipleimages from the camera 104 and determine the direction of movement ofthe occupant 110 in the images, for example, by comparing pixel mappingsof two or more images. The remote processor may also receive multipleimages from the camera 108 and determine the direction of movement ofthe occupant 110 in the images based on the images, for example, bycomparing pixel mappings of two or more images. The processor maycompare the directions of movement of the occupant 110 from the imagescaptured by the cameras 104, 108 to determine whether one or twooccupants are present. If the comparison indicates the same direction ofmovement, the processor may conclude that the same occupant 110 wascaptured by the cameras 104, 108. If the comparison indicates differentdirections of movement, the processor may conclude that the occupant 110captured by the cameras 104, 108 are two different occupants.

In some example embodiments, a processor (e.g., the processor shown inFIG. 3 or 4) may determine whether the occupant 110 in the imagescaptured by the camera 104 and the occupant 110 in the images capturedby the camera 104 are the same occupant based on a motion of theoccupant 110 in the images captured by the first camera 104 and a motionof the occupant 110 in the images captured by the second camera 108.

To illustrate, the processor may determine a change(s) in pixel mappingof the occupant 110 in images captured by the camera 104 by comparingmultiple images of the occupant 110 captured by the camera 104. Theprocessor may also determine a change(s) in pixel mapping of theoccupant 110 in images captured by the camera 108 by comparing multipleimages of the occupant 110 captured by the camera 108. If the changes inthe images captured by the camera 104 and the changes in the imagescaptured by the second camera 108 correlate well with each other, theprocessor may determine that the cameras 104 and 108 captured the sameoccupant, the occupant 110. In such cases, the occupant 110captured/detected by the camera 104 and the occupant 110captured/detected by the second camera 108 count as a single occupant.

If the changes in the images captured by the camera 104 and the changesin the images captured by the second camera 108 do not correlate wellwith each other, the processor may determine that the occupant 110detected by the camera 104 and the occupant 110 detected by the camera108 are different occupants and, thus, count as two occupants. Theprocessor may use a threshold value of a correlation parameter todetermine whether the occupant 110 captured/detected by the camera 104and the occupant 110 captured/detected by the camera 108 are the sameoccupant.

In some example embodiments, the processor may perform both comparisonof directions of movement as well as determination of correlation ofmotion of occupants captured in images from different cameras todetermine whether the same or different occupants are captured in theimages from the different cameras.

By determining that two or more cameras do not have a common visualfield, occupants captured/detected by the cameras can be determined tobe distinct occupants. When two or more cameras have a common visualfield, performing comparison of directions of movement and/ordetermining correlation of motion of occupants captured/detected by thecameras enables determining whether the same or different occupants arecaptured/detected by the cameras. By integrating cameras withluminaires, information about the proximity or spatial relationshipbetween the luminaires that is established, for example, during thecommissioning of the luminaires, may be used to determine whether therespective cameras have a common visual field.

In some example embodiments, the system 100 may include more or fewerluminaires than shown in FIG. 1. In some example embodiments, imagesensors other than cameras may be used. In some example embodiments,each camera may include a processor. The cameras shown in FIG. 1 may bedisposed in different locations than shown, and different kinds ofluminaires may be included in the system 100. In some alternativeembodiments, the cameras 104, 108, 116 may be positioned external to theluminaires 102, 106, 114.

FIG. 2 illustrates an image 200 captured with a camera of the system ofFIG. 1 according to an example embodiment. Referring to FIGS. 1 and 2,the image 200 may be captured, for example, by the camera 104 of FIG. 1.In the image 200, two occupants 202, 204 are present, where the firstoccupant 202 is across a table from the second occupant 204. Asdescribed above with respect to FIG. 1, in some example embodiments, thenumber of pixels, pixel intensity, and other parameters related to theoccupants 202, 204 in the image 200 may be used to detect the presenceof the occupants 202, 204.

In some example embodiments, the camera 108 of the luminaire 106 mayalso capture an image that includes the occupants 202, 204, and theoccupants 202, 204 in the image captured by the camera 108 may also bedetected based on the number of pixels, pixel intensity, and otherparameters related to the occupants 202, 204 in the image.

In some example embodiments, without determining whether the occupants202, 204 detected by one image sensor (e.g., the camera 104) are thesame or different occupants detected by another image sensor (e.g., thecamera 108 or the camera 116), determining the total number of occupantsmay be challenging. For example, the total number of occupants may bemistakenly determined to be four if a common visual field of the cameras104, 108 is not considered. By determining whether the cameras 104, 108have a common visual field, further analysis may be performed to moreaccurately determine the total number of occupants. For example, themotions of the occupants 202, 204 in the image 200 captured by thecamera 104 and the motions of the occupants in the image captured by thecamera 108 may be analyzed to determine the level of correlation, forexample, with respect to a threshold value of a correlation parameter asdescribed above. Thus, by first determining whether the cameras 104,108, 116 have a common visual field, the number of occupants in an areamay be more accurately determined.

FIG. 3 illustrates a system 300 of occupant detection according to anexample embodiment. As illustrated in FIG. 3, the system includes aluminaire 302, a luminaire 304, and a processor 306. The luminaire 302may include the camera 308, and the luminaire 304 may include the camera312. The camera 308 may include a data storage 310, and the camera 312may include a data storage 314. The data storages 310, 314 may be memorydevices such as SRAMs integrated in the cameras 308, 312, respectively.Alternatively, the data storages 310, 314 may be memory devices such asflash memories that are unpluggable or otherwise easily removable.

In some example embodiments, the data storages 310, 314 may be used tostore images captured by the cameras 308, 312. The image datacorresponding to images captured by the camera 308 may be transferred tothe processor 306 via a connection 316 with or without being stored atthe data storage 310. The image data corresponding to images captured bythe camera 312 may also be transferred to the processor 306 via aconnection 320 with or without being stored at the data storage 314.

In some example embodiments, each camera 308, 312 may detect occupantsand transfer the detection information to the processor 306.Alternatively or in addition, the processor 306 may process the imagedata from each of the cameras to detect occupants in the respectiveimage data. For example, the luminaire 302 may be one of the luminaires102, 106, 114, and the luminaire 304 may be another one of theluminaires 102, 106, 114, and the luminaires 302, 304 may operate in thesame manner as described above with respect to the luminaires 102, 106,114. As described above with respect to the cameras in FIG. 1, eachcamera 308, 312 may not only detect occupants but may also determinedirections of movement of occupants detected by the particular camera.

Alternatively or in addition, the processor 306 may determine directionsof movements of occupants detected by the cameras 308, 312 or by theprocessor 306. For example, processor 306 may determine whether thecameras 308 and 312 have a common visual area in the same manner asdescribed with respect to FIG. 1. For example, the processor 306 maydetermine whether a light (encoded with identifier information of theluminaire 302) emitted by the luminaire 302 is received by the luminaire304. To illustrate, the camera 312 may receive the emitted light andtransfer the information to the processor 306. The processor 306 mayalso determine whether a light (encoded with identifier information ofthe luminaire 304) emitted by the luminaire 304 is received by theluminaire 302. To illustrate, the camera 308 may receive the emittedlight and transfer the information to the processor 306.

In some example embodiments, a processor 306 may determine whether oneor occupants in images captured by the camera 308 and in images capturedby the camera 312 are the same occupant(s) based on motions of theoccupant(s) determined from the captured images. To illustrate, theprocessor 306 may determine a change(s) in pixel mapping of an occupantdetected in images captured by the camera 308 by comparing multipleimages of the occupant captured by the camera 104. The processor 306 mayalso determine a change(s) in pixel mapping of an occupant in imagescaptured by the camera 312 by comparing multiple images of the occupantcaptured by the camera 312. If the changes in the images captured by thecamera 308 and the changes in the images captured by the second camera312 correlate well with each other, the processor 306 may determine thatthe cameras 308, 312 had captured the same occupant. Otherwise, theprocessor 306 may determine that the cameras 308, 312 had captured themultiple occupants, as described above.

The system 300 may determine a total number of occupants by determiningwhether different cameras have a common visual field and performingfurther processing of captured images to avoid multiple counting of thesame occupants.

FIG. 4 illustrates a system 400 of occupant detection according toanother example embodiment. As illustrated in FIG. 4, the system 400 mayinclude a luminaire 402 and a luminaire 404. The luminaire 402 mayinclude a camera 406 with a data storage 408. The luminaire 404 mayinclude a camera 410 with a data storage 412. The data storages 408, 412may be memory devices such as SRAMs integrated in the cameras 406, 410,respectively. Alternatively, the data storages 408, 412 may be memorydevices such as flash memories that are unpluggable or otherwise easilyremovable.

In some example embodiments, the luminaire 402 may be one of theluminaires 102, 106, 114, in FIG. 1 and the luminaire 404 may be anotherone of the luminaires 102, 106, 114, and the luminaires 402, 404 mayoperate in the same manner as described above with respect to theluminaires 102, 106, 114.

In some example embodiments, the luminaire 404 may include a processor414 that can perform detection of occupants and determine directions ofmovements of occupants based on image data of images captured by thecameras 406, 410. For example, the camera 406 may provide image data ofthe image captured by the camera 406 to the processor 414 via connection416. The camera 410 may provide image data to the processor 414 viainternal connections of the luminaire 404. The processor 414 may alsodetermine whether the cameras 406 and 410 have a common visual area inthe same manner as described with respect to FIG. 1.

In some alternative embodiments, the cameras 406, 410 may performdetection of occupants from the images captured by the respective camera406, 410 and provide the detection information to the processor 414. Thecameras 406, 410 may also determine directions of motions of detectedobjects/occupants and provide the direction information to the processor414, which can perform comparison of the information to determine thenumber of occupants in a similar manner as described above.

In some example embodiments, a processor 414 may determine whether oneor occupants in images captured by the camera 406 and in images capturedby the camera 410 are the same occupant(s) based on motions of theoccupant(s) determined from the captured images in a similar manner asdescribed above.

The system 400 may determine a total number of occupants by determiningwhether different cameras have a common visual field and performingfurther processing of captured images to avoid multiple counting of thesame occupants.

FIG. 5 illustrates a flowchart of a method 500 of occupant detectionaccording to an example embodiment. The method 500 may be used with thesystems 100, 300, and 400 of FIGS. 1, 3, and 4, respectively. Referringto FIGS. 1 and 3-5, at step 502, the method 500 includes determiningwhether the first camera 104, 308, 406 of the first luminaire 102, 302,402 and the second camera 108, 312, 410 of the second luminaire 104,304, 404 have a common visual field. For example, the step 502 may beperformed by the processor 306, 414. At step 504, the method 500 mayinclude detecting, by the first camera 104, 308, 406 of the firstluminaire 102, 302, 402, a first occupant in the common visual field. Atstep 506, the method 500 may include detecting, by the second camera108, 312, 410 of the second luminaire 104, 304, 404, a second occupantin the common visual field. At step 508, the method may includedetermining, by the processor 306, 414, whether the first occupant andthe second occupant are the same occupant in response to determiningthat the first camera and the second camera have the common visualfield.

In some example embodiments, the method 500 may include determining, bythe processor 306, 414, that the first occupant and the second occupantare different occupants in response to determining that the first cameraand the second camera have different visual fields from each other. Themethod 500 may also include determining, by the processor 306, 414, adirection of movement of the first occupant based on images captured bythe first camera 104, 308, 406, and a direction of movement of thesecond occupant based on images captured by the second camera 108, 312,410.

In some example embodiments, the method 500 may include determining, bythe processor 306, 414, whether the first occupant and the secondoccupant are the same occupant is performed by determining a level ofcorrelation between a motion of the first occupant and a motion of thesecond occupant.

Although a particular order of steps are shown in FIG. 6, in somealternative embodiments, different orders of steps may be performedwithout departing from the scope of this disclosure. In some alternativeembodiments, some steps of the method 500 may be omitted withoutdeparting from the scope of this disclosure.

FIG. 6 illustrates a flowchart of a method 600 of occupant detectionaccording to another example embodiment. The method 600 may be used withthe systems 100, 300, and 400 of FIGS. 1, 3, and 4, respectively.Referring to FIGS. 1, 3, 4 and 6, at step 602, the method 600 includesdetermining whether the first camera 104, 308, 406 of the firstluminaire 102, 302, 402 and the second camera 108, 312, 410 of thesecond luminaire 104, 304, 404 have a common visual field. The method600 also includes detecting, by the first camera 104, 308, 406, a motionof a first occupant in the common visual field, at step 604, anddetecting, by the second camera 108, 312, 410, a motion of a secondoccupant in the common visual field, at step 606. At step 608, themethod 600 includes determining whether the first occupant and thesecond occupant are the same occupant by comparing the motion of thefirst occupant and the motion of the second occupant. In some exampleembodiments, comparing the motion of the first occupant and the motionof the second occupant includes determining changes in a pixel mappingof the first occupant, determining changes in a pixel mapping of thesecond occupant, and determining whether the changes in the pixelmapping of the first occupant and the changes in the pixel mapping ofthe second occupant correlate with each other, for example, within athreshold value.

Although a particular order of steps are shown in FIG. 6, in somealternative embodiments, different orders of steps may be performedwithout departing from the scope of this disclosure. In some alternativeembodiments, some steps of the method 600 may be omitted withoutdeparting from the scope of this disclosure.

Although particular embodiments have been described herein, thedescriptions are by way of example. The features of the embodimentsdescribed herein are representative and, in alternative embodiments,certain features, elements, and/or steps may be added or omitted.Additionally, modifications to aspects of the embodiments describedherein may be made by those skilled in the art without departing fromthe spirit and scope of the following claims, the scope of which are tobe accorded the broadest interpretation so as to encompass modificationsand equivalent structures.

What is claimed is:
 1. A system for determining occupancy, the systemcomprising: a first luminaire having a first camera to detect a firstoccupant; a second luminaire having a second camera to detect a secondoccupant; and a processor configured to determine whether the firstcamera and the second camera have a common visual field and to determinewhether the first occupant and the second occupant are a same occupantin response to determining that the first camera and the second camerahave the common visual field, wherein the processor is configured todetermine whether the first camera and the second camera have the commonvisual field based on a light emitted by the first luminaire andreceived by the second luminaire.
 2. The system of claim 1, wherein theprocessor determines a direction of movement of the first occupant basedon images captured by the first camera and wherein the processordetermines a direction of movement of the second occupant based onimages captured by the second camera.
 3. The system of claim 2, whereinthe processor determines whether the first occupant and the secondoccupant are the same occupant based on the direction of movement of thefirst occupant and the direction of movement of the second occupant. 4.The system of claim 1, wherein the processor determines whether thefirst occupant and the second occupant are the same occupant based on amotion of the first occupant and a motion of the second occupant.
 5. Thesystem of claim 1, wherein the light emitted by the first luminaire isreceived by the second camera and wherein the light emitted by thesecond luminaire is received by the first camera.
 6. The system of claim1, wherein the processor determines whether the first camera and thesecond camera have the common visual field during commissioning of thefirst luminaire and the second luminaire.
 7. The system of claim 1,wherein the processor determines the first occupant and the secondoccupant are different occupants in response to determining that thefirst camera and the second camera have different visual fields fromeach other.
 8. The system of claim 1, wherein the first camera transmitsa message indicating a detection of the first occupant to the processorand wherein the second camera includes the processor.
 9. The system ofclaim 1, wherein the first camera is integral to the first luminaire andwherein the second camera is integral to the second luminaire.
 10. Amethod for determining occupancy, the method comprising: determiningwhether a first camera of a first luminaire and a second camera of asecond luminaire have a common visual field; detecting, by the firstcamera of the first luminaire, a first occupant in the common visualfield; detecting, by the second camera of the second luminaire, a secondoccupant in the common visual field; and determining, by a processor,whether the first occupant and the second occupant are a same occupantin response to determining that the first camera and the second camerahave the common visual field, wherein the processor is configured todetermine whether the first occupant and the second occupant are thesame occupant at least by comparing a direction of movement of the firstoccupant against a direction of movement of the second occupant.
 11. Themethod of claim 10, further comprising determining, by the processor,that the first occupant and the second occupant are different occupantsin response to determining that the first camera and the second camerahave different visual fields from each other.
 12. The method of claim10, further comprising determining, by the processor, the direction ofmovement of the first occupant based on images captured by the firstcamera and the direction of movement of the second occupant based onimages captured by the second camera.
 13. The method of claim 10,wherein determining, by the processor, whether the first occupant andthe second occupant are the same occupant is performed by determining alevel of correlation between a motion of the first occupant and a motionof the second occupant.
 14. A system for determining occupancy, thesystem comprising: a first luminaire having a first camera to capture afirst image; a second luminaire having a second camera to capture asecond image; and a processor configured to determine whether the firstcamera and the second camera have a common visual field and to determinewhether a first occupant in the first image and a second occupant in thesecond image are a same occupant in response to determining that thefirst camera and the second camera have a common visual field, whereinthe processor is configured to determine whether the first camera andthe second camera have the common visual field based on a light emittedby the first luminaire and received by the second luminaire, wherein thelight includes identifier information of the first luminaire.
 15. Thesystem of claim 14, wherein the processor determines that the firstoccupant and the second occupant are different occupants in response todetermining that the first camera and the second camera have differentvisual fields from each other.
 16. The system of claim 14, wherein theprocessor determines whether the first occupant and the second occupantare the same occupant based on a direction of movement of the firstoccupant and a direction of movement of the second occupant.
 17. Thesystem of claim 14, wherein the processor determines whether the firstoccupant and the second occupant are the same occupant based on a motionof the first occupant and a motion of the second occupant.